The present invention relates to a synchronizer ring for use in automotive speed variators that has not only high strength and toughness but also improved wear resistance, as well as good synchronization characteristics with respect to the mating member as expressed in terms of friction coefficient.
Synchronizer rings are conventionally made of aluminum bronze, high strength brass and other copper alloys that satisfy the requirements for high strength, high toughness, high wear resistance and high friction coefficient.
A perspective view of a typical synchronizer ring for use in a speed variator is shown in FIG. 1. The inner surface 1 of the ring is subjected to intermittent surface contact with a rotating tapered cone under high pressure and the outer circumference of the ring is provided with spaced chamfers 2 that mesh with chamfers on a mating hub sleeve. In order for the synchronizer ring to exhibit its function, it must have high strength, high wear resistance and high compatibility with the mating member. Synchronizer rings have, therefore, been commonly fabricated of high strength brass and other copper compounds that possess these characteristics.
The demand for reducing the size and weight of automotive speed variators and for increasing their output is constantly growing and this has caused the need to develop a synchronizer ring that offers an even higher strength, toughness, wear resistance and friction coefficient. However, these requirements cannot be fully met by the prior art synchronizer rings made of existing copper alloys such as aluminum bronze and high-strength brass.
The present inventor has, therefore, conducted studies in order to develop a synchronizer ring made of a structural material that is capable of satisfying the above-mentioned requirement of automotive speed variators for a smaller size, a lighter weight and a larger output. As a result, the present inventor has found that this objective can be attained by either one of the following synchronizer rings:
(1) A synchronizer ring made of a Cu alloy that contains 17-40% Zn (all percents being on a weight basis), 2-11% Al and 50-3,000 ppm of oxygen, as well as 0.1-3.5% of at least one of Ti, Zr and V, with at least one optional element selected from among 0-3% of at least one of Fe, Ni and Co, 0-0.3% of at least one of P, Mg and Ca, 0.1-4% Mn, 0.05-1.5% Pb, 0.05-2.5% Sn and 0.005-0.5% Si, and with the balance being Cu and incidental impurities, said alloy having such a structure that intermetallic compounds and oxides are uniformly dispersed in a matrix; or PA1 (2) A synchronizer ring made of a Cu alloy that contains 17-40% Zn (all percents being on a weight basis), 2-11% Al, 0.5-6% Mn, 0.1-2% Si, 0.1-3% of at least one of Fe, Ni and Co, 0.003-0.3% of at least one of P, Mg and Ca, and 30-1,000 ppm of oxygen, with either 0-1% (preferably 0.05-1%) Cr or 0-2% (preferably 0.05-2%) of at least one of Pb and Sn or both being present as optional elements, and the balance being Cu and incidental impurities, said alloy having such a structure that intermetallic compounds and oxides are uniformly dispersed in a matrix. PA1 (1) It contains 17-40% Zn (all percents being on a weight basis), 2-11% Al and 50-3,000 ppm of oxygen, as well as 0.1-3.5% of at least one of Ti, Zr and V and an optional element selected from among 0-3% of at least one of Fe, Ni and Co, 0-0.3% of at least one of P, Mg and Ca, 0-2.5% Sn, 0-0.5% Si, 0-4% Mn and 0-1.5% Pb, and with the balance being Cu and incidental impurities; or PA1 (2) It contains 17-40% Zn, 2-11% Al, 0.5-6% Mn, 0.1-2% Si, 0.1-3% of at least one of Fe, Ni and Co, 0.003-0.3% of at least one of P, Mg and Ca, 30-1,000 ppm of oxygen, and an optional element selected from among 0-1% Cr and 0-2% of at least one of Pb and Sn, and the balance being Cu and incidental impurities. In either case, the Cu alloy has such a structure that intermetallic compounds and oxides are uniformly dispersed in a matrix.
Both of these alloys specified above have high strength, high toughness, as well as high wear resistance and friction coefficient. Therefore, synchronizer rings made of these alloys enable the manufacture of an automotive transmission that is smaller in size and lighter in weight and which exhibits a higher performance.